Following recent postings regarding keyboard touch weight, I thought
that I would share my experience.  Randolph Herr's comments make
perfect sense.  If there were no friction, the down-weight readings of
all keys would be virtually the same.  The difference in the readings
can be due to friction in the moving parts.  When you depress a key,
you have to overcome both friction and the weight of the moving parts
in order to lift the hammer.  When you release the key, friction is
still there, offering resistance against the key's return.  Friction
isn't particular: it works in both directions.  The weight of the
hammer, on the other hand, wants to go in one direction only: down
(gravity).

The action (including the dampers) must work properly and be accurately
regulated.  But just as important is that the correct replacement
hammers are fitted.  The hammers fitted to early Steinways were much
lighter than modern ones and, just to make matters worse, New York
Steinways had completely different hammers from the Hamburg-built
pianos.

When you order replacement hammers you should tell the suppliers the
make, model, and age of the piano, and also the country of origin, to
ensure you get the correct ones.  If your supplier says that they are
all the same, go elsewhere!

In theory there should be no need to re-weight the keyboard after
hammer replacement.  Many years ago I fitted new hammers to a Steinway
Model O Duo-Art Grand, and the keyboard touch weight was then very
heavy.  I was advised (by a Steinway technician) to have the keyboard
re-weighted.  This advice was wrong; the hammers were simply too heavy
for that age of piano.  The end result was a piano that had the correct
down-weight and up-weight, but was horrible to play by hand.

Steve Greatrex
Plymouth, UK